Rotor housing structure for rotary piston engine

ABSTRACT

Herein disclosed is a rotor housing structure for an internal combustion engine of rotary piston type, which comprises a rotor housing substrate formed with an ignition plug hole, an adapter of high heat-conductive material and defining therein a shooting hole, and an electroplated layer. The rotor housing structure further comprises as a novel element an iron sheet of considerable thickness which is interposed between the housing substrate and the electroplated layer. Thus, the adapter has its inner end welded to the iron sheet and accordingly reinforced by the iron sheet which in turn provides an excellent substrate for the electroplate layer.

[ Dec. 3, 1974 nite States Patent [191 Terazawa 3,705,818 l2/l972 Grosseau 204/49 UX 3,722,480 3/1973 Berkowitz...........................123/8.0l

E mm m N mo ST US on Y RR 0A mm RR 4 Primary Examiner-Carlton R. Croyle Assistant Examiner-Michael Koczo, Jr.

Attorney, Agent, or FirmFleit & Jacobson Hiroshima-ken, Japan May 15, 1973 [57] ABSTRACT Herein disclosed is a rotor housing structure for an in- [22] Filed:

ternal combustion engine of rotary piston type, which comprises a rotor housing substrate formed with an ignition plug hole, an adapter of high heat-conductive material and defining therein a shootin electroplated layer. The rotor housin [21] App]. No.: 360,531

g hole, and an g structure furer comprises as a novel element an iron sheet of 5 000 m N 7 H3 6 85 9 mm DW mm y." uhm 1m r. 0m u .l rm 0 W mm D n" 0" "n Um a u" m mm D .J u D. mm mm m1 mm .11 L I. ml C V. M. a .m M U1 1 ll 0 2 3 55 ll considerable thickness which is interposed between Fleld of Search................. 8.0.9, the s g substrate and the electroplated layer. 418/178 204/49 Thus, the adapter has its inner end welded to the iron sheet and accordingly reinforced by the iron sheet [56] References Cited UNITED STATES PATENTS which in turn provides an excellent substrate for the electroplate layer.

3155313 11/1964 Bentele...............................418/178 D 3,512,907 5/1970 Belzner.......................... 123/s.45x 5Clalms,3 raWmgFlgmeS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in engine construction of an internal combustion engine of rotary piston type, and, more particularly, to improvements in a rotor housing structure of the rotary piston engine.

2. Description of the Prior Art I-Ieretofore, there have been two considerable problems concomitant with the engine construction of a rotary piston engine. One of them is that the metal material constituting a rotor housing structure of the rotary piston engine is subjected, during the engine operation, to local over-heating to thereby invite deterioration in mechanical strength of the metal material employed. The other is formation of cracks at the inner peripheral edge of a shooting hole, which will result in degradation of the combustion gas sealing.

In order to solve the above problems, the present Applicant has proposed-such a rotor housing structure as is disclosed in Japanese Utility Model Publication No. 71 20087. In the proposed structure, an adapter which is made of copper or the like metal having a sufficient heat-conductivity is mounted in an ignition plug hole, which is formed in the rotor housing substrate, so as to define therein a shooting hole. As is well known in the art, however, the rotor housing substrate is usually made of light metal alloy and is covered at its inner surface with a hard chromium layer of high wearresistivity. The covering of the chromium layer is, on the other hand, performed by the electroplating process, but the direct application of the particular layer to the rotor housing substrate is known quite difficult. For this reason, according to the common electroplating process, the rotor housing substrate is at first sprayed with a metal such as iron, and then chromium is electroplated on the iron layer. Since, however, the sprayed iron layer itself is considerably brittle and accordingly the brazing of the adapter to the iron layer can not provide firm adhesion inbetween, the overlying chromium layer is liable to peeling so that the chromium strips thus peeled will constitute an obstacle to the rotational motion of the rotor.

In the proposed rotor housing structure, therefore, the chromium layer is omitted or removed on purpose at the position which is to overlie the inner end of the adapter. As a result, an annular groove is necessarily formed between the inner portion of the adapter and the adjacent chromium layer to provide a spacing inbetween, and carbon particles formed in the course of the engine operation will be deposited or gathered in the groove to invite excessive and/or unbalanced wearing of an apex sealing member which is carried on the apex portion of the rotor.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an improved rotor housing structure which is free from cracks which might otherwise be formed at the inner peripheral edge of a shooting hole due to the presence of thermal stress.

Another object of the present invention is to provide an improved rotor housing structure in which peeling of the chromium layer in the vicinity hole is prevented in advance.

According to a major aspect of the present invention, an iron sheet of substantial thickness is interposed or sandwiched between the rotor housing substrate and the chromium layer. The housing substrate is cast to the outside wall of the iron sheet and the iron sheet has an inwardly diverging hole which Fegisters at its outermost end with the innermost end of a shooting hole deof the shooting fined by the adapter. As a result, the adapter has its inner end welded to the iron sheet and reinforced by the iron sheet which in turn provides an excellent substrate for the electroplating of the chromium layer.

BRIEF DESCRIPTION OF THE DRAWING I DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2, generally designated at numeral 10 is an internal combustion engine of rotary piston type, which is provided as customary with a rotor 11 of polygonal shape. This rotor 11 is rotatably received within a multi-lobed rotor housing 12, to a peripheral portion of which an ignition plug 13 is attached to ignite the introduced combustible mixture. As is well known in the art, it is technically difficult to locate a shooting hole 14 of the ignition plug 13 in the vicinity of a water jacket 15, which is formed in the rotor housing 12 for passing therethrough cooling water. In the rotary piston engine 10, moreover, the portion of the rotor housing 12 adjacent to the shooting hole 14 cannot be cooled down so much by the cyclically introduced mixture in comparison with the usual reciprocating'engine. For these two reasons, the metal material constituting the rotor housing 12 is subjected, during, the engine operation, to local over-heating to thereby invite substantial deterioration in mechanical strength of the used metal material, as has been shortly discussed in the beforehand. And, the material of the portion forming the shooting hole 14, in other words, the afore-mentioned adapter has a coefficient of thermal expansion which is quite different from that of the rotor housing substrate. Thus, cracks are formed at the inner peripheral edge of the shooting hole 14, which will rea suit in degradation of the combustion gas sealing therearound, as has also been discussed. Designated at reference numeral 16 is an apex sealing member which is received in the apex portion of the rotor 11 for slidable contact with the inner wall of the rotor housing 12.

Turning now to FIG. 3, a rotor housing structure acwardly reduced shooting hole 14 for allowing an ignition spark of the plug 13 to pass therethrough. Said adapter 18 has an inside wall which is secured, preferably by welding or brazing, to the outside wall of the iron sheet 17. The material of the rotor housing substrate 12 is cast around the iron sheet 17 and the adapter 18. The iron sheet 17 has an inwardly diverging hole which registers at its outermost end with the innermost end of the shooting hole 14 in the adapter 18.

As is apparent from the above description, the adapter 18 has its inner end welded to the iron sheet 17 and accordingly reinforced by the iron sheet 17 which in turn provides an excellent substrate for the electroplated chromium or nickel layer 19. Thus, it should be appreciated that the rotor housing structure of the present invention is free from cracks which might otherwise be formed at the inner peripheral edge of the shooting hole 14 due to the presence of the thermal stress. It should also be appreciated that the possible peeling of the electroplated layer 19 in the vicinity of the shooting hole 14 is precluded as a result of sufi'rcient adhesiveness with the iron sheet 17.

What is claimed is:

l. A rotor housing structure for an internal combustion engine of rotary piston type comprising:

an iron sheet of trochoidal shape and having an inwardly diverging hole;

an adapter formed with an inwardly reduced shooting hole and welded to the outside of said iron sheet with the outermost end of said diverging hole registering with the innermost end of said shooting hole;

a rotor housing substrate cast around said iron sheet and said adapter; and

an electroplated layer covering the inside wall of said N iron sheet. 2. A rotor housing structure according to claim 1, wherein said electroplated layer is made of chromium.

iron sheet. 

1. A rotor housing structure for an internal combustion engine of rotary piston type comprising: an iron sheet of trochoidal shape and having an inwardly diverging hole; an adapter formed with an inwardly reduced shooting hole and welded to the outside of said iron sheet with the outermost end of said diverging hole registering with the innermost end of said shooting hole; a rotor housing substrate cast around said iron sheet and said adapter; and an electroplated layer covering the inside wall of said iron sheet.
 2. A rotor housing structure according to claim 1, wherein said electroplated layer is made of chromium.
 3. A rotor housing structure according to claim 1, wherein said electroplated layer is made of nickel.
 4. A rotor housing structure according to claim 1, wherein said adapter is welded to the outside wall of the iron sheet.
 5. A rotor housing structure according to claim 1, wherein said adapter is brazed to the outside wall of the iron sheet. 